Performance comparison of CSI acquisition schemes for LTE-Advanced based 3D MIMO system

This paper investigates channel state information (CSI) acquisition schemes for LTE-Advanced based 3D MIMO systems. Three different CSI acquisition schemes are introduced and compared with a system-level simulation. Simulation results for the 3D-UMi scenario show that the proposed scheme, i.e., stepwise CSI acquisition scheme based on beamformed CSI-reference signal (RS), achieves either similar or better performance compared to the other CSI acquisition schemes, i.e., non-precoded CSI-RS based scheme and beamformed CSI-RS based scheme with joint selection. The results also show that the proposed scheme is beneficial especially when the number of antennas at a base station (BS) is large. The feasibility of standardization support for these schemes is also analyzed in multiple aspects, e.g., overhead of downlink RS and CSI feedback, system complexity.